Resolve "Add a link to documentation on how to get external ip in the Kubernetes cluster details page"

What does this MR do?

Adds a note and a link to the documentation on how to get the external address of the ingress for clusters.

Are there points in the code the reviewer needs to double check?

The Vue.js flow for the link.

Why was this MR needed?

We don't show the external address anywhere, but it is really needed. First step is to point to documentation.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #42693 (closed)